Self-locking mounting assembly



Jan. 2, 1968 P. c. DOOLEY, JR

SELF-LOCKING MOUNTING ASSEMBLY Filed. April 25,

I INVENTOR. PETER C. DOOLEY,JR.

ATTORNEY United States Patent 3,360,890 SELF-LOCKING MOUNTING ASSEMBLY Peter C. Dooley, Jr., Lewiston, N.Y., assignor to The Carborundum Company, Niagara Falls., N.Y., a corporation of Delaware Filed Apr. 25, 1966, Ser. No. 545,070 3 Claims. (Cl. 51-378) ABSTRACT OF THE DISCLOSURE A self-locking mounting assembly for a grinding wheel having an adapter with a shank for receiving the grinding wheel which is clamped between a flange secured to the shank and a nut. The adapter has an internally threaded bore adapted to mate with a threaded power tool spindle. The last two or three internal threads of the adapter are distorted radially inwardly to provide a lock between the spindle and the adapter.

This invention relates to a mounting assembly and more particularly to a self-locking device for mounting an abrasive wheel on a rotatable spindle.

Normally, abrasive wheels are supported on a mounting device which in turn is suitably threadably secured to an arbor or spindle rotatably driven by a power source in a manner well-known in the art. The wheel mounting assembly is so threaded onto the spindle that under normal operating conditions, the force generated by the grinding action tends to tighten the assembly on the spindle. Quite often when employing a pneumatic source of power, there is a tendency for the spindle to stop suddenly rather than gradually when the power is turned off, thus creating a condition in which the wheel assembly may spin off the spindle resulting in damage to the assembly and possible bodily harm to personnel in the area.

Attempts have been made to solve this problem by employing additional components such as jam nuts, lock washers, etc., and in some installations clamping devices are used which require the spindle to be reworked or replaced. Although these components and clamping devices have served the purpose for which they were designed, they have not been entirely satisfactory due to their unreliability and the excessive costs involved in carrying extra inventory such as jam nuts, lock washers, etc. and in the time-consuming operation of refitting the spindle.

The general purpose of this invention is to overcome the above disadvantages by providing a self-locking clamping or mounting assembly for abrasive wheel's.

It is, therefore, an object of the present invention to provide a new and improved self-locking mounting assembly for an abrasive wheel.

It is another object of the present invention to provide a new and improved wheel mounting assembly having novel means for precluding wheel back-off from a spindle.

It is still another object of the present invention to provide a new and improved self-locking mounting assembly which requires no additional locking components.

It is a further object of the present invention to provide a new and improved wheel mounting assembly which is adapted to be mounted on a conventional power spindle without the necessity of reworking or replacing the spindle.

These and other objects and advantages of the present invention will become more apparent upon consideration of the following detailed description when taken in conjunction with the following drawings, in which:

FIG. 1 is a plan view of the mounting assembly in which a preferred illustrative embodiment of the invention is incorporated;

FIG. 2 is an enlarged sectional view taken on the plane of line 22 of FIG. 1 illustrating the mounting assembly mounted on a threaded spindle and clampingly engaging an abrasive wheel; and

FIG. 3 is a diagrammatic view illustrating the distorted threads of elliptical cross section of the mounting assemblys locking feature.

Referring to the drawings, it will be observed that a mounting assembly constructed in accordance with the principles of this invention comprises an adaptor body, generally designated 10, having a head 12 preferably of a hexagonal configuration (see FIG. 1) and an integral shank 14 of reduced diameter extending therefrom whereby a shoulder 16 having a substantially planer surface perpendicular to the longitudinal axis of said shank, is formed by the transition between the full diameter of the head and the reduced diameter of the shank.

Shoulder 16 constitutes a bearing surface for a driving flange 18 which is preferably press-fitted onto shank 14 and abuts against the bearing surface of shoulder 16. It should be appreciated that the principles of this invention contemplate any suitable means for attaching flange 18 onto shank 14 such as welding, soldering, brazing or bonding, if desired.

Adapter body 10 is provided with internal threads 20 for mating with the external threaded portion 22 of power. tool spindle 24, said internal threads commencing inwardly from the top horizontal planar surface of the head 12 as seen in FIG. 2 and extending to the end of shank 14 remote from said head. A major portion of the internal threads have turns 26 which are round and true having crests 28 which define the minor diameter of a threaded bore of a substantially circular cross section.

The remaining portion of said internal threads which comprise the last few threads adjacent the end of shank 14 remote from head 12 have turns 30 which are substantially elliptical in cross section and have portions 32 adjacent the opposite ends of the minor axis of the elliptical configuration that project radially inwardly of the crests 28 of the major portion of the threads (see FIG. 3).

The elliptical shaped portion constitutes the locking feature and is formed by compressing two opposite sides of the lower portion of the shank after the internal threads 20 have been formed therein so that the minor axis defined by theelliptically shaped threads is of a lesser length than the minor diameter of the major portion of the threads.

After the compressing operation, external threads 34 are cut into the outer surface of shank 14, resulting in a true and round external threaded portion of the shank that extends from the bottom thereof as seen in FIG. 2 upwardly toward shoulder 16.

The clamping means which includes flange 18 also comprises a clamping nut 36 having internal threads 38 cooperable with the external threads 34 of shank 14 for clamping a replaceable abrasive wheel 40 onto shank 14 between the flange 18 and the nut. In the preferred embodiment, nut 36 is provided with spaced holes 42 for accommodating the prongs of a spanner wrench.

The entire assembly is threadably mounted onto the power tool spindle by starting at the head 12 of adapter body 10 and advancing the assembly up the threaded portion of spindle 24 until the elliptically shaped threads are engaged. Threads 22 of the spindle are clamped securely at opposite sides by the force of the radially inwardly distorted portions 32 to provide a locking effect of uniform torque over several threads of the spindle thereby preventing the assembly from backing oif the spindle. It should be appreciated that the internal threads of adapter body 10 allow conventional free running of the adapter body on the spindle up to the last two or three turns whereat the locking effect of the distorted threads is introduced.

Although this invention has been shown and described in connection with a depressed center abrasive wheel, it should be realized that other types of abrasive wheels and work engaging tools may be secured onto a rotatable spindle in the manner hereinbefore set forth within the purview of the principles of this invention.

As a result of this invention, an improved self-locking mounting assembly is provided which does not require additional pieces such as jam nuts, lock washers, etc., and which does not require reworking or replacement of the threaded spindle. Another advantage residing in the device of this invention is that the self-locking feature is effective although the threads of the spindle may be somewhat worn. Moreover, this assembly does not in any way, even with repeated use, damage the spindle. Still another advantage residing in the device of this invention i that galling or seizing of the device on the spindle is precluded as opposed to other conventional mounting devices wherein galling and seizing do occur when subjected to excessive torque.

A preferred embodiment of the principles of this invention having been hereinabove described and illustrated, it is to be realized that modifications thereof can be made Without departing from the broad spirit and scope of this invention as determined by the appended claims.

I claim:

1. A mounting assembly for a grinding tool comp-rising: an adapter body having a head and a shank; a driving flange connected to said shank at said head; said head having a substantially planar surface extending at right angles to the longitudinal axis of said shanks and constituting a bearing surface for a portion of said driving flange; said driving flange being rigidly secured onto the shank at the juncture of said head and said shank and abuttingly engaging said bearing surface; an abrasive grinding wheel mounted on said shank; said shank having an externally threaded portion of uniform diameter; a nut threaded on said externally threaded portion for securing said grinding wheel between said flange and said nut; said driving flange extending radially outwardly substantially beyond said head and said nut; said adapter body having internal threads extending substantially the length of said body and terminating at the end of said shank remote from said head; said threads comprising a plurality of turns; a major portion of said turns having crests of a uniform diameter and being circular in cross section; the remaining portion of said turns adjacent said end of said shank constituting self-locking means having opposed portions projecting radially inwardly beyond said crests and being substantially elliptical in cross section.

2. A mounting assembly for a grinding tool as defined in claim 1 wherein said remaining portion of said turns comprises the last two turns of said internal threads.

3. A mounting assembly for a grinding tool as defined in claim 1 wherein said remaining portion of said turns comprises the last three turns of said internal threads.

References Cited UNITED STATES PATENTS 332,540 12/1885 Law 1512l 2,409,163 10/1946 Stever 51-379 2,791,787 5/1957 Neuschotz 15121 2,899,220 8/1959 Abrams 15121 3,081,808 3/1963 Rosan et al. 151-21 EDWARD C. ALLEN, Primary Examiner. 

